Valorisation of table olive discards: bioactive composition and bioaccessibility of a novel functional ingredient

Abstract

The table olive production industry generates considerable volumes of by-products every year, mainly olives that do not meet established quality standards and are withdrawn from commercial channels despite having nutritionally desirable constituents. This work aims to characterise the fatty acid profile and bioactive compounds of new ingredients obtained from table olive discards, namely table olive powders, and to determine their antioxidant properties and the bioaccessibility of their phenolic fraction. The results reveal that the stuffing ingredients and the drying process do not affect the obtained product's fatty acid profile, and all the samples are high in oleic (68.25 %–72.43 %), palmitic (16.34 %–18.42 %) and linoleic (4.42 %–6.95 %) acids. Hot-air drying treatment affects samples' contents of phenolic compounds and samples' antioxidant properties, which makes freeze-drying (FD) extremely suitable for obtaining high-antioxidant powder. Nevertheless, the total phenol content of all table olive powders (TOPs) evaluated was high, with values ranging from 5933.3 to 8141.9 mg GAE/kg of dry weight (DW). After in vitro digestion, hydroxytyrosol (HT), recognised as health-promoting agent, presents the highest bioaccessibility, with values exceeding 100 %. This finding suggests that the digestive process may release antioxidant compounds from their precursor forms, thereby enhancing the functionality of TOPs. This research has shown that table olive discards can be a valuable source of bioactive compounds, exhibiting considerable potential for substituting conventional chemical additives, such as antioxidants, and for the innovation of novel ingredients in new formulations intended for human consumption.